In general, a sheet conveying unit includes a sheet loading tray to load a sheet and a discharge tray to load a discharged sheet. JP4-308129A discloses the sheet loading tray and the discharge tray are arranged on vertical direction to be mutually separated, and a part of the sheet loading tray serves for the discharge tray. Therefore the unit and the installation area is capable of being small.
However if the sheet conveying unit is mounted on a multi-functional machine having two or more functions including a copying machine, a printer, a facsimile apparatus, etc, a discharge tray for a recording sheet is necessary in addition to a sheet loading tray and another discharge tray. Here, the sheet loading tray and the discharge tray for a loaded sheet do not serve as a discharge tray for a recording sheet. Therefore, the sheet conveying unit has problem that the discharge tray for a recording sheet must be arranged independently under the sheet conveying unit and the height of the unit cannot be lowered.